Buggy code:
public class GenericTypeOperationHandler extends BatchModeCommandHandler { private static final int DASH_OFFSET = 22 ; protected final String commandName ; protected final String idProperty ; protected final String nodeType ; protected final ArgumentWithValue profile ; protected final ArgumentWithValue name ; protected final ArgumentWithValue operation ; protected final Set < String > excludedOps ; protected final ArgumentWithoutValue helpProperties ; protected final ArgumentWithoutValue helpCommands ; private final Map < String , CommandArgument > staticArgs = new HashMap < String , CommandArgument > ( ) ; private Map < String , ArgumentValueConverter > propConverters ; private Map < String , CommandLineCompleter > valueCompleters ; private Map < String , OperationCommandWithDescription > customHandlers ; private GenericTypeOperationHandler . WritePropertyHandler writePropHandler ; private Map < String , OperationCommand > opHandlers ; public GenericTypeOperationHandler ( CommandContext ctx , String nodeType , String idProperty ) { } public GenericTypeOperationHandler ( CommandContext ctx , String nodeType , String idProperty , String ... excludeOperations ) { } public void addValueConverter ( String propertyName , ArgumentValueConverter converter ) { } public void addValueCompleter ( String propertyName , CommandLineCompleter completer ) { } public void addHandler ( String name , OperationCommandWithDescription handler ) { } @ Override public CommandArgument getArgument ( CommandContext ctx , String name ) { } @ Override public Collection < CommandArgument > getArguments ( CommandContext ctx ) { } private OperationCommand getHandler ( CommandContext ctx , String op ) throws CommandLineException { } @ Override public boolean hasArgument ( CommandContext ctx , String name ) { } @ Override public boolean hasArgument ( CommandContext ctx , int index ) { } @ Override public void addArgument ( CommandArgument arg ) { } @ Override protected void recognizeArguments ( CommandContext ctx ) throws CommandFormatException { } @ Override public ModelNode buildRequestWithoutHeaders ( CommandContext ctx ) throws CommandFormatException { } @ Override protected void handleResponse ( CommandContext ctx , ModelNode opResponse , boolean composite ) throws CommandFormatException { } protected StringBuilder formatResponse ( CommandContext ctx , ModelNode opResponse , boolean composite , StringBuilder buf ) throws CommandFormatException { if ( opResponse . hasDefined ( RESULT ) ) { final ModelNode result = opResponse . get ( RESULT ) ; if ( composite ) { final Set < String > keys ; try { keys = result . keys ( ) ; } catch ( Exception e ) { throw new CommandFormatException ( ( "Failed<seq2seq4repair_space>to<seq2seq4repair_space>get<seq2seq4repair_space>step<seq2seq4repair_space>results<seq2seq4repair_space>from<seq2seq4repair_space>a<seq2seq4repair_space>composite<seq2seq4repair_space>operation<seq2seq4repair_space>response<seq2seq4repair_space>" + opResponse ) ) ; } for ( String key : keys ) { final ModelNode stepResponse = result . get ( key ) ; buf = formatResponse ( ctx , stepResponse , false , buf ) ; } } else { final ModelNodeFormatter formatter = Factory . forType ( result . getType ( ) ) ; if ( buf == null ) { buf = new StringBuilder ( ) ; } formatter . format ( buf , 0 , result ) ; } } if ( opResponse . hasDefined ( RESPONSE_HEADERS ) ) { final ModelNode headers = opResponse . get ( RESPONSE_HEADERS ) ; final Set < String > keys = headers . keys ( ) ; final SimpleTable table = new SimpleTable ( 2 ) ; for ( String key : keys ) { <START_BUG> table . addLine ( new String [ ] { key , headers . get ( key ) . asString ( ) } ) ; <END_BUG> } if ( buf == null ) { buf = new StringBuilder ( ) ; } else { buf . append ( LINE_SEPARATOR ) ; } table . append ( buf , false ) ; } return buf ; } @ Override protected void printHelp ( CommandContext ctx ) throws CommandLineException { } protected void printProperties ( CommandContext ctx , List < Property > props ) { } protected void printNodeDescription ( CommandContext ctx ) throws CommandFormatException { } protected void formatText ( CommandContext ctx , CharSequence text , int offset ) { } protected void formatProperty ( CommandContext ctx , String argName , final CharSequence descr ) { } protected void printSupportedCommands ( CommandContext ctx ) throws CommandLineException { } protected List < String > getSupportedCommands ( CommandContext ctx ) throws CommandLineException { } protected List < Property > getNodeProperties ( CommandContext ctx ) throws CommandLineException { } protected ModelNode getOperationDescription ( CommandContext ctx , String operationName ) throws CommandLineException { } protected ModelNode initRequest ( CommandContext ctx ) throws CommandFormatException { } private abstract class ActionHandler implements CommandHandler , OperationCommand { protected Map < String , CommandArgument > args = Collections . emptyMap ( ) ; void addArgument ( CommandArgument arg ) { } @ Override public boolean isAvailable ( CommandContext ctx ) { } @ Override public boolean isBatchMode ( CommandContext ctx ) { } @ Override public void handle ( CommandContext ctx ) throws CommandLineException { } @ Override public CommandArgument getArgument ( CommandContext ctx , String name ) { } @ Override public boolean hasArgument ( CommandContext ctx , String name ) { } @ Override public boolean hasArgument ( CommandContext ctx , int index ) { } @ Override public Collection < CommandArgument > getArguments ( CommandContext ctx ) { } } private class WritePropertyHandler extends GenericTypeOperationHandler . ActionHandler { @ Override public ModelNode buildRequest ( CommandContext ctx ) throws CommandFormatException { } } class OpHandler extends GenericTypeOperationHandler . ActionHandler { private final String opName ; OpHandler ( String opName ) { } @ Override public ModelNode buildRequest ( CommandContext ctx ) throws CommandFormatException { } } }

Fix:
table . addLine ( new String [ ] { key + ':' , headers . get ( key ) . asString ( ) } ) ;